Question

3. Using the term incidence, contrast a seasonal endemic infectious disease with an epidemic infectious disease over the course of one year. 4a. Using SARS-CoV as a specific example, describe how epidemiologists can track infections during an epidemic by a) measuring antibody levels (seroconversion) and b) using PCR methods. 4b. During the course of a single infection, which method will detect SARS-CoV earliest? Explain why. 5. An epidemiologist trying to identify the agent causing a novel flesh-eating epidemic infectious disease has isolated skin samples and performed a metagenomics 16S rRNA assay to identify all bacterial species present Given what you know about the human microbiome, why would performing Koch's Postulates successfully be critical to identifying the disease-causing bacterium?

Answer 1

3. Seasonal infectious diseases have pertained to particular seasons. for example the incidence of water-borne diseases like diarrhea, viral hepatitis and typhoid are seasonal-during summer /rainy season. Some infections like respiratory infections can occur at any time of the year with a sudden change in the weather

The term Endemic disease means it affects/pertains to a particular population, environment, or region. For example the incidence of chickenpox that occurs at a foreseeable rate among school children in India and malaria in some areas of Africa.

4a. The introduction of molecular epidemiology allows the tracking of pathogens based on genotyping of the involved strains from outbreaks and this has revolutionized the management of outbreaks.

The culprit, SARS coronavirus (SARS-CoV), can be detected in patient specimens by RT-PCR detection of viral RNA (targeting the polymerase 1 B region of the genome.) in clinical samples, growth of the virus in cell culture, or serologic detection of specific antibody to SARS-CoV.

4b. Early diagnosis of SARS-CoV infection is imperative for averting future epidemics. Culturing of SARS-CoV is demanding and insensitive. Sandwich enzyme-linked immunosorbent assays (ELISAs) are useful for the detection of SARS-CoV nucleocapsid protein in clinical specimens and ELISAs are cost-effective and more convenient to perform. The RT-PCR (reverse transcription– polymerase chain reaction) and quantitative RT-PCR (qRT-PCR) has been the working standard in diagnosis as they are more sensitive and effective.